In GSM communication networks, rogue base stations capable of intercepting phone calls are commonly referred to as IMSI catchers (IMSI standing for International Mobile Subscriber Identity). When cellular phones are near an IMSI catcher they generally receive a stronger signal from the IMSI catcher than a cellular base station tower at a distance. With a stronger signal, the IMSI catcher can cause the cellular phone to establish communications with the IMSI catcher rather than a legitimate cellular base station tower. Once the cellular phone is in communication with the IMSI catcher, calls initiated by a user of the cellular phone can be intercepted by a user of the IMSI catcher, thereby compromising the cellular phone user's privacy.